So I just went for a nice little cruise, and I realized that my 91 isn't fast enough. I hit full throttle in 1st, 2nd, and 3rd gear, still wanting more. I've had this bike for a year now, and it's my first bike. Maybe I'm just stupid, bitching about mid to high 3 second 0-60 times, but I need something faster. Are there any engine mods that I can do to this bike to speed it up? I'm talking rebuilding the bike with a bigger bore piston or a bigger engine altogether... I just think I'm going to outgrow this bike very soon.

 

Have the head shaved. Re-jet the carbs. Better exhaust...and learn to ride better too...Believe it or not, the rider makes the bike perform...
RB

 

yeah, I'd try losing ten pounds or something, that'd probably speed it up a bit...

 

LOL elmer too funny.

 

Jack it up and put a new 600RR under it, that'll speed it up.

 

Hah, I'm 160, can't lose 10 lbs... I like the idea of shaving the head though... How much can I machine it before I mess up the valvetrain geometry? And the 600rr's are too uncomfortable.

 

You have to be careful you dont shave the head too much otherwise it'll change the compression ratio and you'll need thicker head gaskets etc. Get a machine shop to do it for you. If your going down this route, get it polished, ported, skimmed. These will add a little more horsepower but should make riding it a bit better too. You can even go as far as third angle grinding on the valve seats etc. Higher compression pistons, the list goes on. But its all down to how much money you wanna spend. No need to overbore it and the other stuff i mentioned, it'll end up too expensive, you'd be better off buying a new engine for it. Well not new obviously. Allegedly the carbed versions of the CBR engine are better so maybe buy something from a FX/FY the last of the carbed models. Otherwise your talking of new looms etc. If your willing to get looms and stuff get and RR.

Be careful of putting a blade engine in. The bike will be mega quick but a real handfull. These were known as CBR69's and are wheelie happy. Good luck!!!

 

In shaving the cylinder head, I want higher compression. Putting in a thicker head gasket would just put me back at square one. I believe the compression ratio is 11.3:1 or something like that, wouldn't mind bumping it up to 12:1. Might have to retard the timing a bit, and for sure I'll need 93 octane to prevent pre-detonation, but I think it'll work. Ya, I'll definately take it to a machine shop. At work (Toyota) we run a belt sander over the cylinder heads each time we do a head job. This just makes everything nice and smooth, and takes out small imperfections. I wouldn't do that to my baby though.

 

u dont use 93 octane now??

 

just stick a 900rr motor in and be done with it